Question

Dada a função f(x)=x²-9, determine

a) os valores de a,b e c

b) os valores de x' e x''

c) x'+x''

Answer 1

Vamos lá:

$f\left(x\right)=x^2-9\\f\left(x\right)=x^2+0x-9\\-------\\a=1\\b=0\\c=-9\\-------\\\Delta =b^2-4ac\\\Delta =0^2-4\cdot 1\cdot \left(-9\right)\\\Delta =36\\-------\\x=\frac{-b\pm \sqrt{\Delta }}{2a}\\x=\frac{-0\pm \sqrt{36}}{2\cdot 1}\\\\x'=\frac{\sqrt{36}}{2}=\frac{6}{2}=3\\x''=\frac{-\sqrt{36}}{2}=-\frac{6}{2}=-3\\-------\\x'+x''=3+(-3)\\x'+x''=3-3=0$
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Espero ter ajudado!